From 52500ae864f96360bb76011c251cf1e6a5d2b234 Mon Sep 17 00:00:00 2001
From: Nigel Barnes <ngbarnes@gmail.com>
Date: Fri, 9 Aug 2024 18:54:05 +0100
Subject: New working systems ------------------- MCG-85 [Nigel Barnes]

---
 src/mame/mame.lst          |  3 ++
 src/mame/trainer/mcg85.cpp | 85 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 88 insertions(+)
 create mode 100644 src/mame/trainer/mcg85.cpp

diff --git a/src/mame/mame.lst b/src/mame/mame.lst
index 40dcc085313..35ecd106f48 100644
--- a/src/mame/mame.lst
+++ b/src/mame/mame.lst
@@ -45053,6 +45053,9 @@ emma2                           // 1979 L.J.Technical Systems
 @source:trainer/instruct.cpp
 instruct                        //
 
+@source:trainer/mcg85.cpp
+mcg85                           //
+
 @source:trainer/mk14.cpp
 mk14                            //
 mk14vdu                         //
diff --git a/src/mame/trainer/mcg85.cpp b/src/mame/trainer/mcg85.cpp
new file mode 100644
index 00000000000..f3273101249
--- /dev/null
+++ b/src/mame/trainer/mcg85.cpp
@@ -0,0 +1,85 @@
+// license:BSD-3-Clause
+// copyright-holders:Nigel Barnes
+/******************************************************************************
+
+    Atlantis Computers MCG-85
+
+    After RESET press SPACE on terminal for Expeditor to detect baud rate (50-19.2K).
+
+******************************************************************************/
+
+#include "emu.h"
+
+#include "bus/rs232/rs232.h"
+#include "cpu/i8085/i8085.h"
+#include "machine/i8155.h"
+
+
+namespace {
+
+class mcg85_state : public driver_device
+{
+public:
+	mcg85_state(const machine_config &mconfig, device_type type, const char *tag)
+		: driver_device(mconfig, type, tag)
+		, m_maincpu(*this, "maincpu")
+	{ }
+
+	void mcg85(machine_config &config);
+
+private:
+	required_device<i8085a_cpu_device> m_maincpu;
+
+	void mem_map(address_map &map);
+	void io_map(address_map &map);
+};
+
+
+void mcg85_state::mem_map(address_map &map)
+{
+	map(0x0000, 0x0fff).rom();
+	map(0x1000, 0x1fff).ram(); // optional RAM
+	map(0x2000, 0x20ff).mirror(0x700).rw("i8155", FUNC(i8155_device::memory_r), FUNC(i8155_device::memory_w));
+}
+
+void mcg85_state::io_map(address_map &map)
+{
+	map(0x20, 0x27).rw("i8155", FUNC(i8155_device::io_r), FUNC(i8155_device::io_w));
+}
+
+
+static DEVICE_INPUT_DEFAULTS_START( terminal )
+	DEVICE_INPUT_DEFAULTS( "RS232_TXBAUD", 0xff, RS232_BAUD_9600 )
+	DEVICE_INPUT_DEFAULTS( "RS232_RXBAUD", 0xff, RS232_BAUD_9600 )
+	DEVICE_INPUT_DEFAULTS( "RS232_DATABITS", 0xff, RS232_DATABITS_7 )
+	DEVICE_INPUT_DEFAULTS( "RS232_PARITY", 0xff, RS232_PARITY_EVEN )
+	DEVICE_INPUT_DEFAULTS( "RS232_STOPBITS", 0xff, RS232_STOPBITS_1 )
+DEVICE_INPUT_DEFAULTS_END
+
+
+void mcg85_state::mcg85(machine_config &config)
+{
+	I8085A(config, m_maincpu, 6.144_MHz_XTAL);
+	m_maincpu->set_addrmap(AS_PROGRAM, &mcg85_state::mem_map);
+	m_maincpu->set_addrmap(AS_IO, &mcg85_state::io_map);
+	m_maincpu->in_sid_func().set("rs232", FUNC(rs232_port_device::rxd_r));
+	m_maincpu->out_sod_func().set("rs232", FUNC(rs232_port_device::write_txd));
+
+	I8155(config, "i8155", 6.144_MHz_XTAL / 2);
+
+	rs232_port_device &rs232(RS232_PORT(config, "rs232", default_rs232_devices, "terminal"));
+	rs232.set_option_device_input_defaults("terminal", DEVICE_INPUT_DEFAULTS_NAME(terminal));
+}
+
+
+ROM_START( mcg85 )
+	ROM_REGION(0x1000, "maincpu", ROMREGION_ERASE00)
+	ROM_SYSTEM_BIOS( 0, "24", "Expeditor Monitor V2.4" )
+	ROMX_LOAD("expdr_monitor_2.4.bin", 0x0000, 0x0800, CRC(54a75a26) SHA1(f19294599e8b89a7036ffd1b7a97026d71837c5a), ROM_BIOS(0))
+ROM_END
+
+} // anonymous namespace
+
+
+//    YEAR  NAME    PARENT  COMPAT  MACHINE   INPUT   CLASS         INIT         COMPANY                FULLNAME   FLAGS
+COMP( 1981, mcg85,  0,      0,      mcg85,    0,      mcg85_state,  empty_init,  "Atlantis Computers",  "MCG-85",  MACHINE_NO_SOUND_HW )
-- 
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